Using [11C]raclopride, a radioligand already demonstrated to be affected by dopamine (DA) release from methylphenidate and amphetamine (AMP) studies, this study will observe a decrease in Bmax measures with AMP challenge in both schizophrenic (SCZ) patients and normal controls. Through the appropriate PET imaging protocol it is expected that the magnitude of the decrease in Bmax to be greater in SCZ patients than in the controls. It is also expected that there will be no significant change in NMSP binding with AMP challenge in either.